Heated seats stopped working

[Cutac]

Hello

After I did interior cleaning on my VTS, neither of my heated seats work. I didn't kneel on the seat, I just reclined and slid them a lot. Fuse is OK, light on heater control works.
What to check next?

[EDC5]

You need to measure the resistance of the heater pad. If your car is anything like my C5 there is a module under the seat responsible for the seat heating.

You need to find the connector that leads to the heating pads and measure the resistance with a multimeter. It should be on the order of a few ohms.

[GiveMeABreak]

A hell of a job to strip the seat and replace them; they are known to fail over time as the heating elements compact and break. Maybe it’s time to get the thermal trousers out!

[Cutac]

I doubt's it's the heating elements because both seats stopped working the same day.

Okay, I'll check the connections and will try to measure what I can.

Are seats hard to remove?

[EDC5]

That's very odd that they should both fail simultaneously. On my car each seat's heated seat module received an enable signal from the BSI before they would work. Perhaps this signal is no longer reaching your seats?

[Cutac]

Could be, but why would that happen?
Maybe some wire got undone while I was vacuuming.
I mean, seats themselves are definitely not at fault. I'll check Diagbox for heated seats setting, maybe something got bugged.

I've tried to look under the seats but it's impossible, due to 2 door layout. That's why I'd like to take the seats out, and reconnect everything.

[GiveMeABreak]

I didn’t read your post properly, where you mentioned BOTH seats. In that case , very likely fuse.

Edit:
Fuse F39, 20 Amp, passenger compartment fusebox for your C4.

[Cutac]

Fuse seems to be good, will check it again tomorrow.
Also, take in mind that seat control light works.

[GiveMeABreak]

The rheostat lighting for the heated seats may be coming direct from the BSI control wire, so we must consider that.

Ok, so you have checked Fuse F39. There are 2 pads in each seat - the seat pad and the backrest pad - are these both not working?

The circuit, apart from the F39 fuse in the passenger compartment fuse box is supplied by a Maxi Fuse in the engine compartment fuse box - MF6, so I would have a look at that too....

Here's the diagram

Follow wire BF06 and you can see that it goes from the passenger compartment fuse F39 back to the Maxifuse 6 in the engine bay fusebox.

[white exec]

Likely there will be a relay or two - considerable current is involved.

[Fake Concern]

It's really easy to get the seats out on a C4 Coupe just four Torx bolts (can't remember size offhand). You undo bolts at one end then slide seat to other end to take out remaining bolts. Take the headrests off first to give more space when removing the seats from the car.

By the way my heated seats never worked!

[Cutac]

Ok, so you have checked Fuse F39. There are 2 pads in each seat - the seat pad and the backrest pad - are these both not working?

The circuit, apart from the F39 fuse in the passenger compartment fuse box is supplied by a Maxi Fuse in the engine compartment fuse box - MF6, so I would have a look at that too....

Follow wire BF06 and you can see that it goes from the passenger compartment fuse F39 back to the Maxifuse 6 in the engine bay fusebox.

Yes, both pads in both seats. They were working right before I cleaned the car, so I'd bet they're not faulty.

How to recognize MF6? I won't be able to trace the wire and manual says nothing about any MF6 fuse.

Likely there will be a relay or two - considerable current is involved.

How to check relays for faults?
I'm planning on doing this with the battery unplugged.

It's really easy to get the seats out on a C4 Coupe just four Torx bolts (can't remember size offhand). You undo bolts at one end then slide seat to other end to take out remaining bolts. Take the headrests off first to give more space when removing the seats from the car.

By the way my heated seats never worked!

Ok, thanks. So those bolts are keeping the assembly in place or do they just prevent the seat from sliding off the rails?
Any short wires to watch out for?

[GiveMeABreak]

Likely there will be a relay or two - considerable current is involved.

No relays for the heated seats Chris - I've checked all the BSI and Engine Fuse box relays and none shown for the seats.

The Maxi Fuse 6 supplies the passenger compartment Fuse box specifically (BFH5), which contains fuses F36 to F40.

These supply:

• F36 - 20A radio with amplifier
• F37 - 30A electrically controlled driver´s seat
• F38 - 30A (not Used)
• F39 - 20A heated seats

So still worth checking out, as according to VIN you don't have use for F37 (electric seats), but you should have the Equaliser Amp fitted that utilises F36 - so is that still working?

Finally, I can suggest that if you've been cleaning the floor area by the left hand side (LHD Driver's Side), check the wiring that goes back to the BSI under the carpet as shown below:

Also the earthing point for the seats is MC55 and that is located here:

[Fake Concern]

Ok, thanks. So those bolts are keeping the assembly in place or do they just prevent the seat from sliding off the rails?
Any short wires to watch out for?

The rails come off with the seats, so tip seat foward and unplug the wiring once the bolts are out.

[Cutac]

No relays for the heated seats Chris - I've checked all the BSI and Engine Fuse box relays and none shown for the seats.

The Maxi Fuse 6 supplies the passenger compartment Fuse box specifically (BFH5), which contains fuses F36 to F40.

These supply:

• F36 - 20A radio with amplifier
• F37 - 30A electrically controlled driver´s seat
• F38 - 30A (not Used)
• F39 - 20A heated seats

So still worth checking out, as according to VIN you don't have use for F37 (electric seats), but you should have the Equaliser Amp fitted that utilises F36 - so is that still working?

Finally, I can suggest that if you've been cleaning the floor area by the left hand side (LHD Driver's Side), check the wiring that goes back to the BSI under the carpet as shown below:

I think the amp still works, I mean, I've still got sound and nothing changed.

Ok, thanks, I'll check fuses and wiring tomorrow.

The rails come off with the seats, so tip seat foward and unplug the wiring once the bolts are out.

Ok, thanks


One quick question so I don't open a new topic.
Bought a new 3 button key for 2011 c4 from aliexpress and it doesn't work. It's been cut and synchronized to the BSI(car starts with it), but remote functions don't work. Battery is new. Any ideas?